Aspirating non-reuseable syringe

ABSTRACT

An aspirating non-reuseable syringe is provided which includes a plunger. The main components of the plunger include a piston and a cylindrical plunger stem. The piston is removably connected to the cylindrical plunger stem by first, second, and third connecting members. The connecting members utilize a nipple mating with one aperture and sliding within another aperture to effect aspiration as well as disconnection of the piston from the plunger stem after a single use of the syringe.

FIELD OF THE INVENTION

This invention relates in general to a plunger for a non-reuseablesyringe, and more particularly to a non-reuseable syringe which isincapable of being used more than once for making an injection and yetis capable of aspirating fluids. The non-reuseable syringe utilizes aplunger that includes three connecting members which disconnect theplunger stem from the plunger piston after insertion of the plunger intothe housing of the syringe in order to expel the contents of thesyringe.

BACKGROUND OF THE INVENTION

In the United States and throughout the world, the multiple use ofhypodermic syringe products which are intended for single use only isinstrumental in drug abuse and more particularly in the transfer ofcontagious diseases. Such contagious diseases include AIDS andhepatitis. The transfer is most prevalent in intravenous drug users whoroutinely share and reuse syringes, but can also be a problem for themedical community if proper precautions to prevent multiple use ofdisposable syringes are not followed. Furthermore, the effects ofmultiple use are a major concern in third world countries where repeateduse of syringe products may also be responsible for the spread of manydiseases.

Many attempts have been made to remedy this problem. Some earlyattempted solutions involved destruction of the syringe after use eitherby using a destructive device or providing a syringe assembly withfrangible zones so that the syringe could be rendered inoperable by theapplication of force. Although many of these devices work quite well,they require the specific intent of the user followed by the actual actto destroy or render the syringe inoperable. None of these devices iseffective with a user having the specific intent to reuse the syringe.

Accordingly, there is a need for a non-reuseable syringe which becomesinoperative or incapable of further use automatically without anadditional act on the part of the user. Co-owned U.S. Pat. No.5,215,524, issued Jun. 1, 1993, the contents of which are herebyincorporated by reference, discloses a single use syringe which utilizesa disconnecting plunger stem. This syringe becomes inoperativeautomatically after a single use.

However, the need for a non-reusable syringe must be met withoutpreventing the filling or use of the syringe under normal conditions.One such use under normal conditions includes the ability to aspiratefluid using the syringe. It is common in the medical community toaspirate fluid during the use of a syringe (i.e., to alternately retractand extend the plunger of the syringe without expelling all contents ofthe syringe). This ability to aspirate must still be available with asingle use syringe, and is not available with the syringe of U.S. Pat.No. 5,215,524.

Although various types of single use non-reuseable syringes have beenproposed, the severity of the AIDS epidemic and the need for solutionsto the above problems continuously provide a need for other types ofnon-reuseable syringes, particularly those which also provide foraspiration.

SUMMARY OF THE INVENTION

This continuous need is met, and the problems of multiple use of priorsyringes overcome, by the plunger for a non-reuseable syringe of thesubject invention, as well as by the syringe utilizing such plunger.

The main components of the plunger of the subject invention include apiston and a cylindrical plunger stem hollow at an open end thereof. Thepiston is removably connected to the cylindrical plunger stem by first,second, and third connecting members. The first connecting member isconnected longitudinally to the piston and extends into the open end ofthe plunger stem. The first connecting member comprises a plurality ofcircumferentially spaced arms extending longitudinally away from thepiston. The circumferentially spaced arms form a first aperture at aninterior thereof and are flared at an exterior thereof on an endopposite the connection to the piston. The second connecting membercomprises a plurality of protrusions extending radially away from asecond aperture. The third connecting member is a longitudinal nippleslidable within the second aperture and matable with the first apertureformed by the circumferentially spaced arms of the first connectingmember. The cylindrical plunger stem has a plurality ofcircumferentially spaced slots extending longitudinally at an open endthereof, and the open end of the hollow cylindrical plunger stemencloses the first, second and third connecting members such that theplurality of protrusions of the second connecting member slide withinthe plurality of slots and are friction fit within the inner diameter ofan outer housing.

To accomplish the non-reuseable feature of the syringe which includesthe plunger of the subject invention, an open end of the plunger stem isconstricted on an interior thereof such that the interior snugly mateswith the flared exterior of the circumferentially spaced arms when thenipple is inserted into the first aperture formed by the interiorthereof.

When the piston which is located at the front end of the plunger isinserted into the rear end of a hollow cylindrical housing of a syringeunit, the wall and the piston form a sealed cavity (with the cylindricalhousing side wall) for containing a liquid within the interior of thehollow cylindrical housing.

Prior to use, and preferably during manufacturing, the nipple is matedwith the first aperture. When the nipple is mated with the firstaperture, the second connecting member is positioned toward the front ofthe slots in the plunger stem. This allows the entire plunger unit to bedrawn back for filling of the syringe, because in this configuration,the interior constricted portion of the cylindrical plunger stem exertspressure on the circumferentially spaced arms. However, the nipplecounteracts such pressure and prevents flexion of the arms inward.Therefore, the piston, plunger stem, and first, second and thirdconnecting members operate as a single unit.

However, the nipple is forced from the first aperture as the protrusionson the second connecting member slide to the rear of the slots in theplunger stem. Any subsequent attempt to draw back the plunger to fillthe syringe with fluid results in the interior constricted portion ofthe cylindrical plunger stem exerting pressure on the circumferentiallyspaced arms. Since the nipple no longer counteracts such pressure, thearms flex inward and the cylindrical plunger stem passes over the firstconnecting member. Thus, the plunger stem, second connecting member, andthird connecting member are disconnected from the piston and the firstconnecting member. Accordingly, the syringe is incapable of beingrefilled because the piston must be withdrawn to create the vacuum forfilling the syringe and to create the cavity for holding the liquidwithin the syringe.

The resulting non-reuseable single use syringe can thus be used toprevent multiple use of syringes, such as disposable hypodermicsyringes. This is accomplished by providing the piston/syringe asdiscussed in further detail below.

The syringe according to the subject invention is also capable ofaspiration due to the use of the sliding third connecting member (thenipple) within the second aperture. The nipple can slide within theaperture a distance equal to the length of the slots before the secondconnecting member (the plurality of protrusions) contacts the end of theslots and thereby forces the nipple out of the first aperture. Thus, oneis able to move the plunger back and forth within the limitations of theslot length without disengaging the plunger stem. This allows foraspiration using the syringe as is also discussed in further detailbelow.

BRIEF DESCRIPTION OF THE FIGURES

These and other objects, features and advantages of this invention willbe evident from the following detailed description of preferredembodiments when read in conjunction with the accompanying drawings inwhich:

FIG. 1 is a partially cut away isometric view of a plunger which is oneembodiment of the subject invention;

FIG. 2 is a side view of a non-reuseable syringe including the plungershown in FIG. 1, shown prior to withdrawal of the plunger to fill thesyringe;

FIG. 3 is a cross sectional view of the non-reuseable syringe shown inFIG. 2;

FIG. 4 is a partial isometric view of the rear end of the plunger shownin FIG. 1;

FIG. 5 is a side view of the non-reuseable syringe of FIG. 2 indicatingthe position of the syringe elements during insertion of the plungerinto the hollow cylindrical housing;

FIG. 6 is a cross sectional view of the non-reuseable syringe shown inFIG. 5; and

FIGS. 7 and 8 are side views of the non-reuseable syringe of FIG. 2showing the aspiration feature of the syringe accomplished by slidingthe nipple within the aperture without disconnecting the nipple from theaperture.

DETAILED DESCRIPTION OF THE INVENTION

The main components of one preferred embodiment of the subject inventionare depicted in FIGS. 1-8. As shown in FIGS. 1 and 4, the plunger 12comprises a cylindrical plunger stem 30 closed at its rear end 38 andhollow at least at the other front end 34. At the front end 34 of theplunger stem 30 a piston 14 provides a liquid sealing means. The closedrear end 38 and the piston 14 form an interior 54 of the plunger 12.Toward the front end 34 of the plunger 12, slots 32 extendlongitudinally around the circumference of the plunger stem.

The plunger stem 30 is connected to the piston 14 by a first connectingmember 16, a second connecting member (made up of aperture 27 andprotrusions 28), and a third connecting member 26. As shown in FIGS. 2and 6, the first connecting member 16 is connected longitudinally to thepiston 14, or may be integral therewith, and comprises a plurality ofcircumferentially spaced arms 18 extending longitudinally away from thepiston 14. The arms 18 form a first aperture 20 at their interior, thepurpose of which is discussed in further detail below. At the exteriorend 22 of the arms away from the connection to the piston, the arms areflared. The first aperture 20 is mated with the third connecting member,a longitudinal nipple 26. The second connecting member includes aplurality of protrusions 28 which extend radially away from a secondaperture 27 to form a friction fit within the inner diameter of an outerhousing (see below) and also slideably fit within the slots 32 of theplunger stem 30. This is best shown in FIGS. 2 and 3. The nipple 26slides within this second aperture 27. The interior surface at the frontend of the plunger stem forms a constricted end 36, such that the frontend 34 of the plunger stem 30 snugly fits against the arms 18 of thefirst connecting member 16. The flared end 22 of the first connectingmember 16 mates with the constricted end 36 of the interior of theplunger stem 30 (see FIG. 2).

The plunger 12 is snugly inserted into a hollow cylindrical housing 40of a syringe 10 (see FIGS. 2 and 5). The hollow cylindrical housing 40is closed at its front end 42 by a wall 44, to which a needle can bemounted via a mounting means 48. Syringe needles are generally marketedwith a plastic-type bracket on one end thereof. This plastic-typebracket mounts to the mounting means 48. The bracket may snugly slideover the mounting means 48, or the mounting means could be provided withgrooves into which corresponding ridges on the bracket are twisted.Various means for connecting syringe needles are known in the art andcan thus be used in the subject invention to mount a needle to themounting means. A needle so mounted in the wall 44 is in fluidcommunication with the interior 46 (see FIG. 2) of the housing 40.

In order to prevent tampering with the connecting members in an attemptto reuse the syringe, removal of the plunger 12 is prevented by one-wayflanges 52 at the rear end 50 of the housing 40. These flexible flangesare angled so that insertion of the plunger is possible but removal isnot possible due to the contact of the protrusions 28 of the secondconnecting member 24 with the flanges 52. When the flanges extend intothe interior of the housing, the diameter of the second connectingmember protrusions 28, which are friction fit within the housing 40, issuch that the second connecting member cannot pass through the housingat the position of the flanges.

Having described one embodiment of the plunger and non-reuseable syringeof the subject invention, its use is best illustrated in FIGS. 2 and 5,and 7 and 8. As shown in FIG. 2, the initial position of the elements ofthe syringe 10 prior to withdrawal (so as to fill the syringe) areillustrated. The plunger 12 is fully inserted into hollow cylindricalhousing 40, so that the piston 14 is adjacent the wall 44 at the frontend 42 of the housing 40. The nipple 26 is mated with the aperture 20and the protrusions 28 are positioned slideably within and toward thefront of the slots 32. A cross section illustrating the position of thesyringe elements taken through the second connecting member is shown inFIG. 3. In this position, the nipple 26 prevents withdrawal of theplunger stem 30 without simultaneous withdrawal of the piston 14. Thisis because withdrawal of the plunger stem 30 causes the constrictedfront end 36 of the plunger stem 30 to exert a rearward force on theflared ends 22 of the first connecting member's arms 18. The nipple 26prevents the arms 18 from flexing inward in response to this force.Accordingly, the entire plunger 12 unit is pulled rearward in onemotion, so as to fill the syringe.

Upon forward motion of the plunger stem 30 to an extent greater than thelength of the slot 32, as shown in FIG. 5, the second connecting memberincluding the plurality of protrusions 28 slides to the rear of theslots 32 and the nipple 26 is no longer mated with the aperture 20. FIG.6 illustrates a cross section of the syringe at the position of theflared ends of the arms at this point of an injection stroke. Anysubsequent rearward movement of the plunger stem therefore results inanother rearward force on the flared ends of the first connectingmember's arms. The removal of the nipple allows the arms to flex inward,allowing the constricted end of the plunger stem to pass thereby. Theplunger stem, second connecting member, and third connecting member arethus withdrawn, but the piston and first connecting member remain withinthe housing and no longer operate in conjunction with the plunger stem.As should be readily apparent, the syringe is then incapable of beingused again because movement of the piston is necessary to create thevacuum for filling of the syringe.

FIGS. 7 and 8 illustrate the aspiration feature of the subjectinvention. The syringe (beginning as shown in FIG. 2) plunger stem 30 iswithdrawn in the hollow cylindrical housing 40 to the point shown inFIG. 7. The plunger stem 30 is then pushed back into the hollowcylindrical housing 40 to the position shown in FIG. 8. At this point,the nipple 26 remains mated within the first aperture 20 of the firstconnecting member 16, by sliding within the second aperture 27 of thesecond connecting member. The plunger stem 30 can be alternatelywithdrawn and pushed into the hollow cylindrical housing 40 in thisfashion for aspiration until the plurality of protrusions 28 of thesecond connecting member contact the rear of the slots 32. At that time,the second connecting member will pull the nipple 26 out of the firstaperture 20 of the first connecting member 16 and render the syringeincapable of further use, as shown in FIG. 5.

Thus, the amount of aspiration possible can be controlled by controllingthe length of the slots and the length of the longitudinal nipple. Byextending the slot and providing a nipple which can slide within thesecond connecting member, this aspiration feature is attainable.

It should be readily apparent to those skilled in the art that anysuitable materials, such as plastic and rubber, can be utilized for thevarious syringe elements.

The syringe which includes the plunger as described above is assembledas follows. The piston 14 and the first connecting member 16 arepositioned at the front end 42 of the hollow cylindrical housing 40. Thethird connecting member 26 is positioned in the aperture 27 of thesecond connecting member, and both members so connected are thenpositioned within the cylindrical plunger stem 30 so that theprotrusions 28 of the second connecting member extend through the slots32 of the cylindrical plunger stem 30. At this point, the rear end 38 ofthe plunger stem 30 is not closed or sealed, but remains hollow (seebroken lines on FIG. 4). The hollow cylindrical plunger stem 30, withthe second and third connecting members positioned within the plungerstem, is snugly inserted into the hollow cylindrical housing 40 untilthe third connecting member 26 contacts the first connecting member 16at the front of the hollow cylindrical housing 40. A rigid device, suchas a wire or even a pencil-like member, is inserted into the hollowcenter 54 of the plunger stem 30 to exert a forward force on the thirdconnecting member 26. This causes the nipple 26 (of the third connectingmember) to mate with the first aperture 20 of the first connectingmember 16. The rigid device is then removed from the center of theplunger stem, and the rear end 38 of the plunger stem is sealed orclosed by suitable means. For example, a plastic plug may be inserted orinjected, or a cap can be permanently applied to the end of the plungerstem. The end is permanently sealed so that future tampering with thesecond and third connecting members is not possible. This prevents thesyringe from being "re-set", i.e., by forcing the third connectingmember nipple forward to mate with the first aperture. After the end ofthe plunger stem is sealed, the syringe is ready for use. Accordingly,after any required aspiration and a single dispensing use, the syringeof the subject invention cannot be used again because the plunger stemseparates from the piston. This prevents subsequent filling with liquid.

The subject invention thus provides a method of preventing multiple useof a syringe comprising the steps of: selecting the single use syringeof the subject invention as disclosed above; drawing a liquid into thesingle use syringe; and dispensing the liquid from the single usesyringe. When the liquid has been dispensed from the single use syringe,the syringe cannot again be used to draw a liquid into the syringe dueto the separation of the piston from the plunger stem upon anysubsequent withdrawal of the plunger body. The invention also provides amethod of aspirating using a single use syringe by alternately pushingand drawing the plunger without unmating the nipple of the syringe.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions and the like can bemade without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the following claims.

What is claimed is:
 1. A plunger for an aspirating single use syringecomprising:a cylindrical plunger stem being hollow at an open endthereof, said plunger stem having a plurality of circumferentiallyspaced slots extending longitudinally at said open end thereof and beingconstricted on an interior of said open end thereof; a piston attachedto said open end of said plunger stem; a first connecting memberconnected to said piston and extending into said open end of saidplunger stem, said first connecting member comprising a plurality ofcircumferentially spaced arms extending longitudinally away from saidpiston, said circumferentially spaced arms forming a first aperture atan interior thereof and said circumferentially spaced arms flared at anexterior thereof on an end opposite said connection to said piston; asecond connecting member comprising a plurality of protrusions extendingradially away from a second aperture, said second connecting memberpositioned within said plunger stem so that said plurality ofprotrusions slide within said plurality of slots; and a third connectingmember comprising a longitudinal nipple slidable within said secondaperture and matable with said first aperture, wherein when said nippleis mated with said first aperture, the flared circumferentially spacedarms of said first connecting member snugly mate with said constrictedinterior of said plunger stem.
 2. The plunger of claim 1 wherein saidfirst connecting member is integral with said piston.
 3. An aspiratingsingle use syringe comprising:a hollow cylindrical housing closed at itsfront end by a wall so as to form an interior thereof; means formounting a needle in said wall, wherein when said needle is mounted insaid wall, said needle is in fluid communication with the interior ofsaid hollow cylindrical housing; and a plunger, said plungercomprising:a cylindrical plunger stem being hollow at an open endthereof, said plunger stem having a plurality of circumferentiallyspaced slots extending longitudinally at said open end thereof and beingconstricted on an interior of said open end thereof; a piston attachedto said open end of said plunger stem; a first connecting memberconnected to said piston and extending into said open end of saidplunger stem, said first connecting member comprising a plurality ofcircumferentially spaced arms extending longitudinally away from saidpiston, said circumferentially spaced arms forming a first aperture atan interior thereof and said circumferentially spaced arms flared at anexterior thereof on an end opposite said connection to said piston; asecond connecting member comprising a plurality of protrusions extendingradially away from a second aperture, said second connecting memberpositioned within said plunger stem so that said plurality ofprotrusions slide within said plurality of slots; and a third connectingmember comprising a longitudinal nipple slidable within said secondaperture and matable with said first aperture, wherein when said nippleis mated with said first aperture, the flared circumferentially spacedarms of said first connecting member snugly mate with said constrictedinterior of said plunger stem, said piston of said plunger snuglyinserted into an open rear end of said hollow cylindrical housing andslidable within said hollow cylindrical housing, and said radialextension of said plurality of protrusions contacting the interior ofsaid hollow cylindrical housing such that said second connecting memberfriction fits within said interior of said hollow cylindrical housing.4. A method of preventing multiple use of a syringe which methodcomprises the steps of:selecting the single use syringe of claim 3 fordispensing a liquid therefrom; positioning said nipple within said firstaperture and drawing a liquid into said single use syringe, wherein saiddrawing comprises drawing said plunger away from said front end of saidhollow cylindrical housing, causing said protrusions to position at aforward end of said slots; and dispensing the liquid from the single usesyringe, wherein said dispensing comprises pushing said plunger towardsaid front end of said hollow cylindrical housing, causing saidprotrusions to position at a rearward end of said slots thereby removingsaid nipple from said first aperture; wherein when said liquid has beendispensed from said single use syringe, said syringe cannot again beused to draw a liquid into said syringe due to the removal of saidnipple from said first aperture, such that subsequent drawing of saidplunger causes said constricted interior on the front end of saidplunger stem to compress said flared exterior of said circumferentiallyspaced arms, thereby disengaging said plunger stem from said piston andsaid first connecting member.
 5. A method of preventing multiple use ofan aspirating syringe which method comprises the steps of:selecting thesingle use syringe of claim 3 for aspirating and dispensing a liquidtherefrom; positioning said nipple within said first aperture anddrawing a liquid into said single use syringe, wherein said drawingcomprises drawing said plunger away from said front end of said hollowcylindrical housing, causing said protrusions to position at a forwardend of said slots; alternately pushing said plunger toward said frontend of said hollow cylindrical housing and drawing said plunger awayfrom said front end of said hollow cylindrical housing, such that saidnipple slides within said second aperture and said protrusions slidewithin said slots without contacting said rearward end of said slots,thereby aspirating with said single use syringe; and dispensing theliquid from said single use syringe by pushing said plunger toward saidfront end of said hollow cylindrical housing and contacting saidprotrusions with said rearward end of said slots, thereby removing saidnipple from said first aperture; wherein when said liquid has beendispensed from said single use syringe, said syringe cannot again beused to draw a liquid into said syringe due to the removal of saidnipple from said first aperture, such that subsequent drawing of saidplunger causes said constricted interior on the front end of saidplunger stem to compress said flared exterior of said circumferentiallyspaced arms, thereby disengaging said plunger stem from said piston andsaid first connecting member.